The present invention relates to an automatic processor for a silver halide photosensitive photographic material, and more specifically to an automatic processor for a silver halide photosensitive photographic material which is excellent in high speed processing capability and stability of continual ejection, tends not to result in ejection problems due to clogging, liquid dripping, and the like, and further, improves processability of photosensitive materials such as high rates of processing, uniform dye forming properties, and the like.
In recent years, due to a marked increase in the number of minilabs, the processing amount of photosensitive materials per minilab apparatus has decreased and the solution replacement ratio of photographic processing solution in photographic material processing tanks has decreased. Due to this, processing solutions tend to deteriorate, resulting in instability of processability. Furthermore, for simple-type automatic processors which are installed in minilabs, requirements such as minimal maintenance such as no cleaning of devices and materials as well as curtailment of daily devices and material management have been increased.
In order to meet such requirements, "Japanese Patent Publication Open to Public Inspection No. 6-324455", and the like disclose techniques in which a processing solution which processes silver halide photosensitive photographic materials is placed in a tightly sealed vessel (for example, a processing means placed in a tightly sealed vessel such as an ink jet head), and the processing solution is supplied to the emulsion surface of the photosensitive material through air.
The head of the ink jet system disclosed in the above-mentioned patent publication is required to form highly detailed images. Accordingly, it is constituted so as to spray very fine droplets. Due to that, the supplied amount of a processing solution is fairly small. Thus, if this technique is employed as a processing solution supplying means without any modification, the amount of the processing solution supplied to the emulsion surface of a photosensitive material tends to be insufficient. Particularly, the amount of the color developing agents necessary for carrying out processing becomes absolutely insufficient to increase the reaction time during said processing.
Furthermore, for example, "U.S. Pat. No. 4,901,093" discloses a technique which enables high speed processing by increasing the number of ink jet ejecting nozzles (that is, orifices). However, it has been found that when this technique is merely applied to a processing apparatus which processes silver halide photosensitive photographic materials, the supplied solution amount is still not sufficient.
Further, with this technique, it has been found that in order to maintain more stable ejection of the processing solution, naturally, required is maintenance such as minimization of clogging by cleaning the head section employed as a processing solution supplying means, and the orifices themselves tend to clog.
Further, "Japanese Patent Publication Open to Public Inspection No. 6-324455" describes a technique which mainly processes photosensitive materials for a redox amplification process. It has also found that the silver amount applied to the photosensitive material for the redox amplification process is far less than that of common photosensitive materials, and when the technique is specifically applied to the processing of silver halide photosensitive materials to which the present invention is applied, sufficient effects cannot be obtained and the commercial application is not viable.
Further, a technique described in Japanese Patent Publication Open to Public Inspection No. 9-211832 is one which is developed based on an ink jet system in thermal development. Therefore, this technique has not solved problems with processing particular to silver halide photosensitive photographic materials, to which the present invention is applied, that is, problems with ejection stability during continual ejection of a processing solution, and the like.
As described above, in recent years, the number of minilabs are rapidly increasing, along with demand for more rapid processing. In such situations, demanded is the introduction of an automatic processor which exhibits ease of management of the apparatus and associated materials, and further, is capable of high speed processing.
However, because the above-mentioned ink jet head is primarily constituted to spray very minute liquid droplets, it cannot supply a sufficient amount of the processing solution necessary for adequate reaction. In addition to this, when driving operation is carried out in such a manner that the processing solution is simultaneously ejected from a plurality of orifices over a long period of time and the like, problems occur in which it is difficult to stably supply the necessary amount of the processing solution. Due to this, technical problems which will inevitably be solved are a large increase in the ejection amount of the processing solution, as well as the achievement of stable ejection.
In order to solve these problems, it is enumerated that for example, the driving frequency of a conversion element is subjected to high frequency, or the driving voltage is subjected to high voltage. However, by so doing, the supplied amount of the processing solution is secured, but to the contrary, the formation of the meniscus of the orifice section becomes unstable, which degrades the ejection stability.
In order to prevent this degradation, the number of ejection channels may be increased. However, that results in problems of higher cost, and the difficulty to increase the integration degree of orifices.
The increase in the number of orifices provided in an ejection channel is effective in terms of high possibility to supply a sufficient amount of processing solution. However, it has been found that when an aqueous solution such as a processing solution for silver halide photosensitive photographic materials is ejected, a sufficient ejection amount is not still obtained, and further, the required ejection stability is also not realized.
In addition, differing from an ordinary ink jet printer, it is necessary to continue the ejection of a processing solution from all orifices (nozzles) over a long period of time. Accordingly, it has been found that the conventional orifice constitution tends to result in ejection problems.
As is well known, processing solutions, for silver halide photosensitive photographic materials, are different from inks for ink jet printing sheets of paper, and the main component is water without comprising an organic solvent at all. Due to that, as the contact area with air increases, drying tends to occur due to evaporation. Furthermore, because the concentration of inorganic salts in the photographic processing solution is higher than that of ordinary inks, deposits of inorganic salts tend to occur due to localized drying. Accordingly, serious problems occur in which the clogging of the orifice is caused.
Furthermore, it has newly been found that air bubbles tend to be mixed into the processing solution, because the processing rate during continual processing, employing the processing solution supplying means, is higher than ink jet. The formation of air bubbles may result in pressure loss in the ejection chamber and is likely to result in ejection problems. It has also been found that once the air bubbles are mixed in the ejection chamber, it is very difficult to remove those bubbles from the ejection chamber.